Reducing transmitter’s luminous surface with integrated LED arrays for deep-sea wireless optical communication

Abstract

： Underwater wireless optical communication (UWOC) is suitable to be used in deep-sea, because the water is clear and the background is darkness. Recently, light emitting diode (LED) are preferred in such communication, because it has up to 120°divergence angle, which makes establishing optical link easier. To enlarge the output power of transmitter, there are several discrete LED chips in the light source usually. However, transmitter with more discrete LEDs is disadvantageous to reduce luminous surface, which is related with UWOC equipment's resistance to water pressure. In this paper, a method is presented to reduce such influence by using integrated LED arrays. Firstly, an integrated LED array is designed with seven blue chips series-connectedly. Then, a compact transmitter is developed with four such arrays. The test results show that the transmitter has up to 20Mbps modulation rate with 5.38W optical power. Using this transmitter, it is hopeful to realize 20Mbps speed and more than 100m distance with a suitable high sensitivity receiver in deep-sea. The performance of this transmitter is nearly the same with the ones in previous sea trials, while the effective luminous surface is reduced. These results demonstrate the effectiveness of transmitter with integrated LED arrays. Method in this paper is useful and pragmatic for deep-sea UWOC application.